초록 ▼

A Viterbi decoder for recovering the original bit data stream that was convolutionally encoded as a code symbol stream in a Code Division Multiple Access (CDMA) mobile communication system. The decoder simultaneously decodes at the several data rates associated with certain multirate vocoders. The d

A Viterbi decoder for recovering the original bit data stream that was convolutionally encoded as a code symbol stream in a Code Division Multiple Access (CDMA) mobile communication system. The decoder simultaneously decodes at the several data rates associated with certain multirate vocoders. The decoder can decode at an unknown data rate in either continuous or framed packet modes. It accomplishes this by simultaneously decoding at multiple rates and by creating one or more data quality metrics for each decoded data packet. Special input and output buffering is provided to isolate the decoder from system timing constraints. The input buffer includes selection and accumulation logic to organize code symbol data into the packet order for repeat mode or random burst mode at lower frame data rates. Decoded data packets for each of several predetermined data transfer rates are held in an output buffer for about half of the decoding cycle, thereby permitting the system microprocessor to examine and select the appropriate decoded data packet. The decoder also can be reconfigured to operate at any one of several predetermined convolutional encoding algorithms. The Viterbi decoder, implemented as a single monolithic integrated circuit, can be used in any and all of many different multiuser telecommunications channels.

대표청구항 ▼

[ We claim:] [1.] A method of providing decoded bit data in response to a transmission of code symbol data which represents original bit data having a data rate R.sub.i, where R.sub.i is one data rate of two or more predetermined original bit data rates, the method being executable using a decoder a

[ We claim:] [1.] A method of providing decoded bit data in response to a transmission of code symbol data which represents original bit data having a data rate R.sub.i, where R.sub.i is one data rate of two or more predetermined original bit data rates, the method being executable using a decoder apparatus including an input buffer, a convolutional decoder, and an output buffer, the method including the steps of:transmitting said code symbol data in frames of predetermined time duration wherein the transition between each said successive frame of said code symbol data is forced to a predetermined state;receiving and storing successive portions of said transmission of said code symbol data in said input buffer; anddecoding any portion of said successive portions in said convolutional decoder in two or more passes to obtain two or more rackets {P.sub.i } of decoded bit data, each packet P.sub.i being decoded during a respective pass of said two or more passes, each packet P.sub.i including:decoded bit data I.sub.i corresponding to original bit data having said data rate R.sub.i ; andquality metric data Q.sub.i representing symbol error conditions in said any portion and data error conditions in said decoded bit data; and storing said two or more packets in said output buffer,wherein said quality metric data Q.sub.i representing data error conditions in each said frame of said decoded bit data includes:a Quality Metric (QM) representing the results of a comparison between a predetermined Quality Threshold (QT) value and a measure of the probability of decoding said zero state at said each transition between successive frames of said decoded bit data.